linux-kernel - Re: [PATCH] i2c: cadence: Avoid fifo clear after start

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Message-ID: <pi4mct77spgoef3mfth7qcha73qrzlmvxhjrqrdf5rjfcxzlb4@zwxbyxf3httv>
Date: Wed, 17 Jan 2024 22:05:47 +0100
From: Andi Shyti <andi.shyti@...nel.org>
To: "Boddu, Sai Pavan" <sai.pavan.boddu@....com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>, 
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "Simek, Michal" <michal.simek@....com>, 
	Lars-Peter Clausen <lars@...afoo.de>, Wolfram Sang <wsa@...nel.org>
Subject: Re: [PATCH] i2c: cadence: Avoid fifo clear after start

Hi,

> >> b/drivers/i2c/busses/i2c-cadence.c
> >> index de3f58b60dce..6f7d753a8197 100644
> >> --- a/drivers/i2c/busses/i2c-cadence.c
> >> +++ b/drivers/i2c/busses/i2c-cadence.c
> >> @@ -633,6 +633,7 @@ static void cdns_i2c_mrecv(struct cdns_i2c *id)
> >>
> >>  	if (hold_clear) {
> >>  		ctrl_reg &= ~CDNS_I2C_CR_HOLD;
> >> +		ctrl_reg &= ~CDNS_I2C_CR_CLR_FIFO;
> >
> >I'm wondering whether the whole ctrl_reg should be reset after the first write.

> [Boddu, Sai Pavan] previous implementation of read-modify-write was good then ?

I don't know, I'm just asking... because rather than
read-modify-write, this is read-modify-write-modify-write :-)

I'm just wondering if after the first write ctrl_reg is still
holding a valid value.

Andi